This invention relates to the mechanism of a turnstile in a mass transit system, and, more particularly, to such a mechanism that is operable in a wide variety of conditions.
To gain admission to the fee-paid area of a mass transit station, the patron typically pays a fee and enters through some type of barrier. The barrier is normally locked until the fee is paid, and then is either unlocked or unlocked and opened responsive to the payment of the entry fee, so that the patron may enter through the passageway. The barrier is typically structured so that persons may leave the fee-paid area through the same passageway.
The most common type of barrier is a turnstile, which is a rotatable hub having arms extending therefrom. One of the arms extends across the passageway when the turnstile is at rest in its "home" position. When the fee is paid, the turnstile is unlocked, so that the patron can cause the turnstile hub to rotate in a fee-paid direction by pushing against it with the body or arms. Some turnstiles are supplied with a motor or an energy storage mechanism to assist in the turning of the turnstile hub. The control system or energy storage mechanism of the turnstile is usually arranged so that, after the patron passes through in the fee-paid direction, the next of the arms is positioned to block the passageway. This movement aids in the singulation function, ensuring that only one person can move through the passageway with each fee paid. The turnstile mechanism is also structured to permit persons to exit from the fee-paid area without the payment of a fee, by pushing against the arms to rotate the turnstile hub in the opposite direction.
The mass transit patron typically does not take time to read detailed instructions as to the proper operation of the turnstile, as its use is fairly self evident. However, the patron may unknowingly use the turnstile in a manner that is hard on its mechanism. For example, the patron may lean heavily against the turnstile arm as the payment is inserted into the fare-collection device and the arm and hub are unlocked. This sideways force on the arm may tend to jam or at least prevent the unlocking mechanism from working properly. To ensure unlocking upon demand, powerful unlocking solenoids are typically provided in turnstile mechanisms.
The turnstile system is contacted by each paying customer at least once, and twice if exit is achieved through the turnstile. Additionally, those persons who would attempt to enter the fee-paid area but defeat the fare-collection system encounter the turnstile. One strategy, termed backcocking, to avoid payment is to manually rotate the turnstile hub a short distance in the exit direction so that there is created some additional space between the arms and the adjacent cabinet and to squeeze past the arms.
Since the turnstile is accessible to virtually everyone in the public, the turnstile system is also subject to vandalism. Much of the turnstile mechanism is enclosed in a cabinet housing, leaving the turnstile arms and hub as the most vulnerable components. It is not uncommon for vandals to smash heavy objects against the turnstile, either to gain entry or simply to be destructive. As an example, a person weighing over 200 pounds may jump onto the arm or push against the arm, and in some cases two people may work together to damage the arm or hub mechanism.
In short, the turnstile arms, hub, and mechanism generally can be subjected to demanding conditions by regular patrons, those attempting to use the system but avoid payment, and vandals. The turnstile is operated in a high volume of usage, and it must therefore be able to function for long times between failures while tolerating occasional abuse. The turnstile must retain its smooth, predictable mode of operation through all of these conditions.
A good deal of engineering effort has been directed to the development of turnstile mechanisms, and generally satisfactory units are available commercially. There exists an ongoing need to improve the mechanisms, however. Some remaining areas for improvement are to reduce the susceptibility of the mechanism to damage from loadings of up to 1000 pounds on the arms or hub, reduce the incidence of jamming as a result of loading the arms during operation of the unlocking mechanism, and reduce accessibility of the system to persons who employ sophisticated strategies to gain entrance without payment. Another consideration is that there is an ongoing need to reduce the cost and increase the mean time between failures of the mechanism by making it more rugged. Finally, some transit systems now require that the turnstile be operable for some period of time in a low-power mode on a battery, and the mechanism must consume low levels to meet this requirement. The present invention provides an improved turnstile mechanism meeting these needs, and further provides related advantages.